CHAP, xvr.] SUBJECTIVE PHENOMENA OF SMELL. 13 



prevented, except that gradually effected by admixture through the 

 pharynx and posterior nares. It is through this latter channel that 

 the odorous particles of food, rising from the throat to the nose 

 during expiration, blend the sensation of smell with that of taste so 

 strongly and habitually, that it becomes difficult to discriminate 

 between them. 



Analogy would lead to the belief that the nervous apparatus of 

 smell, if irritated by an internal cause, would be the seat of olfactory 

 sensations. Such subjective phenomena have been known to exist in 

 certain cases of disease, in which the nerve, or the anterior lobe of 

 the brain, has been afterwards found disorganized. Occasionally, 

 too, odours are perceived without the actual presence of the object 

 usually giving rise to them. These also must be regarded as sub- 

 jective. 



The quality of the sense, also, seems to vary not a little in dif- 

 ferent persons; some being strongly affected, even to faintness, by a 

 scent which is almost imperceptible to others. The odours of flowers, 

 for example, are very variously appreciated, as every one must have 

 more or less observed. There are corresponding idiosyncrasies 

 in the other senses. 



On the subjects of this chapter, in addition to the elementary works before 

 quoted, the following may be consulted : Schneiderius, de osse cribriform! et 

 sensu ac organo odoratus ; Scarpa, de organo olfactus ; also, de auditu et olfactu ; 

 Scemm erring, Tcones organi humani olfactus, 1809 ; H. Cloquet, Osphre"siologie, 

 ou traite'des odeurs. Paris, 1821. 



